def solve(string):
    return "Yes" if int(string) >= 30 else "No"
    pass


if __name__ == '__main__':
    import sys
    print(solve(sys.stdin.read().strip())) def solve(string):
    return "Yes" if int(string) >= 30 else "No"
    pass solve return "Yes" if int(string) >= 30 else "No" "Yes" if int(string) >= 30 else "No" int(string) >= 30 int(string) int string 30 "Yes" "No" string string if __name__ == '__main__':
    import sys
    print(solve(sys.stdin.read().strip())) __name__ == '__main__' __name__ '__main__' import sys sys print(solve(sys.stdin.read().strip())) print solve(sys.stdin.read().strip()) solve sys.stdin.read().strip() sys.stdin.read().strip sys.stdin.read() sys.stdin.read sys.stdin sys stdin read strip def solve(string):
    return "Yes" if int(string) >= 30 else "No"
    pass def solve(string):
    return "Yes" if int(string) >= 30 else "No"
    pass solve
def solve(string):
    return "Yes" if int(string) >= 30 else "No"
    pass


if __name__ == '__main__':
    import sys
    print(solve(sys.stdin.read().strip()))
